Method and apparatus for improving the strength of steel bars, especially reinforcing steel



March 20, 1956 A. FRBKJAER-JENSEN 2,733,576

METHOD AND APPARATUS FOR IMPROVING THE STRENGTH OF STEEL BARS,ESPECIALLY REINFORCING STEEL Filed March 30, 1955 5 INVENTOR. BY M Winn, 9II LM 1 M United States Patent ratus Lfor improving the strengthof steel bars, especially reinforcing steel, .by cold work whichcomprises twisting or.-.stretching, or both twisting and stretching, andduring which the steel. bar is held, in the zone of treatment, betweentwo gripping devices, the cold work .being thus applied by relativemovement of the gripping devices.

According to the known methods of ,improving the strength :of steel barsby cold work, .the barshave been fed :to the :zone of :tre'atment fromabove L01 :from the side, while after the operation thebars havebeenzremoved sideways :from the zone of treatment. This involves certainvdisadvantages, of which will be given .further particulars ibelowyandwhich are especially prevalent in case aofz-long bars, whichconsequently, according to .the methods known, :have been. cold-workedin precut-lengths which, chiefly :to facilitate transportation, rarerather-short, forqexample'under'ZOmetres.

11f zthetrawmaterial' istto be cut'into bars ofrfixeddengths,wastage/will occur .atithe rolling mills 'and'furthercwastagewillrliltewise :occur ;at the building sites if the lengths requiredithere-do not correspond to=.the .lengths of the barsithatzrean behandled in the known machines. "lilhe :said disadvantages have beenobviated in the present invention :according to which the steel :bar orbars consist of one or several continuous .strings which inatheintervalstbetween thecold working periods is. or are intermittently conveyed in alongitudinal direction tothe zone .ofitreatmentuforbeing cold workedthere section :by section, the bar :or bars thereby being conveyedutothe zone f :treatment 'through or along the one gripping device andbeing removed-also in the longitudinal direction-from the .zoneoftreatment through :or :along the other gripping'device.

In this-way far greater lengths of reinforcing steel can be handled thanby using the known methods because bars 110 100 metres in length, orlonger, can be handled. The feeding'of the material to thezone oftreatment and its :removal "therefrom require far simpler :feed "devicesthan is the casewith the plants known, and 'thefeeding can -:go i011 ata considerably greater rate than in the latter. The-plant "consequentlyconsumes less-power and has a higher output than known plants of this.type.

"It will further be seen that the'method according to the invention canbe applied to the treatment of steel bars consisting of continuousstrings which are fed to the zone of treatment section by section forsectional cold-working there.

To ensure {treatment of the :entire string, its intermittent feedingmay,.according to the invention, be so arranged that the length of eachfeed movement of the steel string is shorter than or equal to thelengthdfithe zone of treatment, so that no portion of the string. can pathe zone oftreatment without having beenstibjected tocdldsworking. V

This, of course, mayresult in the fact that short portions of the stringwill -be-exposed to cold work twice, which,.however, is of noconsequence, becausea -portion once cold-worked up to a certain strain"is not susceptible o further strain by being againsimilarlycold-worked.

lftthe steel'is .fed as a'continuousrstring, it will, according'tothemethod, be appropriate 'tolfeecl it to the zone of treatment from astoragedrum on which the string :has been coiled from lengths that havebeen'welded one .to anotheryor fronrcoils:as delivered from therolling-mill.

:If a "twisting operation is included in the treatment, itzmaybedesirable to let the portion of .thestring which remains on the storagedrum participate in-the twisting operation, in which "case the :-storagedrum may, according to the invention, 'besupported so'as to be rotatablenot only on an axis transverse to the feed direction but also :on :an:axis parallel :to :the feed direction. When "the steel string leaves'athe zone of :treatment, itmay, according .tothe invention, be conveyedin such amanner that its front .end strikes against ac-stoppwhichdiscontinues the movement :of 'the string, whereupon the'steel is cut,with one orrmorershears, into-any predetermined required lengths, .sothat anyneedless waste in-cutting is avoided. If no special lengths arerequired at :the time of production, thessteelzmay, according totheinvention, either be stored in long lengths of, for example, 25-400metres, or it may becoiledmpon a storage drum, 'from'which it maylateron-be uncoiled and cut into required lengths.

Sometimes, in case of treatment comprising twisting operations, :itwould be desirable to letthe'take-up'drum participate in the twistingmovement, for which reason the drum,-acc0rding to a further laborationof the invention, can :be made'rotatable not only on an axis 'transverseto the direction ofthe string but also on an axis parallel r to it.

sRlants working according to the present method can operatecontinuously, and interruptions "will occur only when changing from onestorage drum to another.

:Even then, however, stoppages can to "some extent be avoided by makingthe steelstr'ing continuous, according to a further elaboration of theinvention, by welding the end of the string unco'iled from one storagedrum to the end ofthe string from the next storage drum. Such weldingmust of course be :made before 'the saidportion of the stringjhasreachedthe zone of treatment, but since each treatment takes some time,sufiicient time is available for preparing-and performing a weldingoperation. In this way any needless waste as cutting .is avoided.

The invention is illustrated below by some instances 'of the machine,reference being made to the appended drawing.

Fig. 'l s'hows a plant for subjecting reinforcing steel to cold :wor kaccording'to the invention, as viewed from theside.

Fig. 2 shows a part of another instance of the ,plant, and

Fig. 3shows apart of still another'instanceof the,pl-ant.

From adrum- 3- '(-Fig 1-) carried by a horizontal axle 2 from a frame1,-and supplied with egg. 1000 metres raw material, the steel string ispassed through -a system or fixed stock .5 through whose,

and116, :whichlcut the steel'into predetermined desirable lengthswhereupon ithesev ran into storage compartments, 4

17;, 18, 19 and 20.

raw material, whichcis supplied either in 'ba-rs or coiled .on the'drum3,

i11 -coils, -.is welded together and shownin [Fig 1,inlengths:051000130001 metres,

dependeat ,on. the thickness of the steel; the machine can-benrade with.two drums so than steel; is being coiled upon one drum while the otherone is in use for the treatment; when the drum used for the treatment isempty, the free end from the empty drum is welded to the free end of thesteel on the drum which has been filled in the meantime, and theproduction in the machine can continue with the minimum degree ofinterruption. Prior to the first start, the machine must be threaded, i.e. the steel must be pulled through from the drum 3 to the grippingdevice 10. When the steel has been inserted in the gripping device 10,the production can commence, and the machine will use the materialcoiled on the drum 3; when the steel has been welded to the steel on theother drum, the machine is restarted without any adjustment, and theprocess continues.

When the machine starts, the gripping devices 6 and 10, which areoperated by pneumatic or hydraulic pressure, will close around thesteel. Then the motor automatically starts and thus, either by a chaindrive 21, see Fig. 1, or by a screw drive or by hydraulic presses, movesthe stock 9, which at the start is at its innermost position, away fromthe other stock 5, causing the steel to be stretched; before, after, orsimultaneously with the commencement of the stretching operation a motor22 is started, which, by means of a belt drive 23 and a gear box locatedin the stock 9, rotates the gripping device so that the steel, which isheld by the gripping device 6, is subjected to twisting. When thedesired stretching and twisting has been accomplished, the grippingdevices 6 and 10 are opened, and the feed rolls 8 are started. The feedrolls 8, which by their rotating movement push the cold-worked steelthrough the stock 9, at the same time pulling fresh steel from the drum3 into the machine, are controlled by an adjustable measuring devicewhich stops the feed when the last section of the cold-worked steelreaches the gripping device 10. While the feed rolls 8 are pulling freshsteel into the machine, the stock 9 slides back to its startingposition, which is reached immediately after the feed rolls havestopped. When the stock 9 has reached its starting position, the shears12 cut the coldworked steel, which is conveyed by the rolls 13 to theshears 14, 15 and 16, which cut it into desired lengths. At the sametime, the gripping devices 6 and 10 are closing around the fresh steel,and the next operation can commence.

Fig. 2 shows a storage drum 3, which is rotatable on two axes 24 and 25at right angles to each other, and Fig. 3 shows a take-up drum 26, whichare rotatable on two axes 27 and 28 at right angles to each other.

I claim:

1. A method of producing cold work steel bar material from a coiledlength of steel rod stock having a crosssectional shape substantiallythe same as that of the bar material to be produced, which consists infeeding a predetermined length of such rod stock from a coil of the samewhile passing the forward end of such length of rod stock through twoclamping chucks located in a predetermined spaced relationship to eachother; clamping each chuck into gripping engagement with the stock sofed so as to prevent relative motion between each such chuck and thesurface of the stock engaged thereby; then twisting the stock locatedbetween such chucks by rotating the chuck last engaged by such stock,about an axis lying parallel to the axis of the stock engaged therebywhile holding the other chuck stationary; then, while both chucks are ingripping engagement with such stock, increasing the distance between thechucks to thereby stretch the stock located between them; then releasingthe gripping engagement of both such chucks with such stock andadvancing the stock extending through such chucks so as to moveadditional stock from said coil into position with relation to both suchchucks; and then repeating said stock twisting and said stock stretchingoperations.

2. A method of processing rod stock to produce cold work bar material,which consists in feeding a predetermined length of such stock from acoil of the same while simultaneously subjecting all portions of thelength so fed to a straightening operation and while moving the forwardend of such length through two clamping chucks located in spacedrelationship to each other; clamping each such chuck into grippingengagement with such rod stock so as to prevent relative movementbetween each such chuck and the surface of the stock engaged thereby;then twisting the stock located between said chucks by rotating one suchchuck about an axis lying parallel to the axis of the stock engagedthereby while holding the other such chuck stationary; then while bothsuch chucks are in gripping engagement with such stock, increasing thedistance between the chucks to thereby stretch the stock located betweenthem; then releasing the gripping engagement of both such chucks withsuch stock and advancing the stock so as to move additional stock fromsaid'coil into position with relation to both such chucks; and thenrepeating said stock-twisting and said stock-elongating operations.

3. A procedure such as defined by claim 1 in which each stock-stretchingoperation is accomplished prior to the stock-twisting of such stock.

4. A procedure such as defined by claim 2 in which each stock-stretchingoperation is accomplished during each stock-twisting operation.

5. A method of processing rod stock to produce cold work bar material,which consists in feeding a predetermined length of such stock from acoil of the same while simultaneously subjecting all portions of thelength so fed to a straightening operation and while moving the forwardend of such length through two clamping chucks located in spacedrelationship to each other; clamping each such chuck into grippingengagement with such rod stock so as to prevent relative movementbetween each such chuck and the surface of the stock engaged thereby;then twisting the stock located between said chucks by rotating one suchchuck about an axis lying parallel to the axis of the stock engagedthereby while holding the other such chuck stationary; then while bothsuch chucks are in gripping engagement with such stock, increasing thedistance between the chucks to thereby stretch the stock located betweenthem; then releasing the gripping engagement of both such chucks withsuch stock and advancing the stock so as to move additional stock fromsaid coil into position with relation to both such chucks; and thensimultaneously severing the twisted and elongated stock to produce barstock of different lengths.

6. Apparatus for producing cold worked steel bars from a continuouslength of rod stock which includes a frame; a coil-supporting spoolrotatably mounted on said frame; a rod-straightening device mounted onsaid frame and adapted to receive rod stock from said spool; a

stock-grippingchuck mounted on said frame in alignment with said device;a chuck support mounted on said frame and movable therealong toward andaway from said chuck; a second stock-gripping chuck mounted on saidsupport in alignment with said first mentioned chuck;

. means for rotating said last mentioned chuck and a plurality ofaligned shears mounted on said frame in alignment with said chucks forsevering rod stock delivered through the chuck mounted on said movablesupport.

References Cited in the file of this patent UNITED STATES PATENTS2,169,824 Tubbs Aug. 15, 1939 2,289,398 Whist July 14, 1942 2,314,151Macklin Mar. 16, 1943- 2,327,103 Gude Aug. 17, 1943: 2,616,478DAvaucourt Nov. 4, 1952 FOREIGN PATENTS 23,040 Great Britain Nov. 2,1898 453,445 Great Britain Sept. 11, 1936 552,677 Great Britain Apr. 20,1943'

1. A METHOD OF PRODUCING COLD WORK STEEL BAR MATERIAL FROM A COILEDLENGTH OF STEEL ROD STOCK HAVING A CROSSSECTIONAL SHAPE SUBSTANTIALLYTHE SAME AS THAT OF THE BAR MATERIAL TO BE PRODUCED, WHICH CONSISTS INFEEDING A PREDETERMINED LENGTH OF SUCH ROD STOCK FROM A COIL OF THE SAMEWHILE PASSING THE FORWARD END OF SUCH LENGTHS OF ROD STOCK THROUGH TWOCLAMPING CHUCKS LOCATED IN A PREDETERMINED SPACED RELATIONSHIP TO EACHOTHER; CLAMPING EACH CHUCK INTO GRIPPINGS ENGAGEMENT WITH THE STOCK SOFED SO AS TO PREVENT RELATIVE MOTION BETWEEN EACH SUCH CHUCK AND THESURFACE OF THE STOCK ENGAGED THEREBY; THEN TWISTING THE STOCK LOCATEDBETWEEN SUCH CHUCKS BY ROTATING THE CHUCK LAST ENGAGED BY SUCH STOCK,ABOUT AN AXIS LYING PARALLEL TO THE AXIS OF THE STOCK ENGAGED THEREBYWHILE HOLDING THE OTHER CHUCK STATIONARY; THEN, WHILE BOTH CHUCKS ARE INGRIPPING ENGAGEMENT WITH SUCH STOCK, INCREASING THE DISTANCE BETWEEN THECHUCKS TO THEREBY STRETCH THE STOCK LOCATED BETWEEN THEM; THEN RELEASINGTHE GRIPPING ENGAGEMENT OF BOTH SUCH CHUCKS WITH SUCH STOCK ANDADVANCING THE STOCK EXTENDING THROUGH SUCH CHUCKS SO AS TO MOVEADDITIONAL STOCK FROM SAID COIL INTO POSITION WITH RELATION TO BOTH SUCHCHUCKS; AND THEN REPEATING SAID STOCK TWISTING AND SAID STOCK STRETCHINGOPERATIONS.